The present invention is directed to a lighting unit designed to provide a uniform illumination of a work area in a room by indirect or reflected light. More particularly, this invention is directed to a luminaire for providing indirect uniform illumination of a work area using a high intensity light source such as a discharge or metal halide lamp. This type of lighting unit is commonly referred to as a luminaire such as the one disclosed in U.S. Pat. No. 4,001,575. The luminaires now in use do not provide for a uniform intensity or uniform dispersion of light over the work area. The reflectors in the luminaires direct the downward going light rays from the lamp upward to be recombined with the direct light rays from the lamp directly above the luminaire creating a hot spot or more intense area of light. The more intense area of light directly above the lamp in turn provides for a more intense light pattern in an area closer to the luminaire at the level of the work area.
The present luminaires or lighting units usually provide a symmetrical lighting pattern covering a full 360.degree. surrounding the luminaire. When placed adjacent to or near vertical surfaces, the lighting units tend to provide more intense light in their immediate vicinity due to the reflection from the nearby or adjacent vertical surface. The uncontrolled reflection from the vertical surface causes a non-uniform illumination at the level of the work area.
The ideal lighting unit or luminaire should generate a controlled light pattern with high light output. The lighting pattern should have a lower intensity directly above the lamp with a linearly increasing intensity moving outward from the area directly above the lighting unit. The lower light intensity directly above the lighting unit will eliminate the undesirable intense area. The reflector will redirect the light rays from the source so that maximum candle power can be achieved at certain predetermined angles within the desired pattern to provide for a uniform dispersion of the light rays to the ceiling or overhead surface and in turn to the work area.
The lighting unit of the present invention generates a 360.degree. symmetric light pattern around the lighting unit. In order to prevent non-uniform light dispersion from nearby or adjacent vertical surfaces, differently shaped baffles have been added to the lighting unit to cut-off the reflected light from vertical surfaces such as walls and/or corners. These baffles redirect both the direct and reflected light rays upwardly and away from the vertial surfaces in predetermined limited patterns.